Social Cost of Alternative Land Development Scenarios
(SCALDS)

The
Intermodal Surface Transportation Efficiency Act (ISTEA) and the Transportation
Equity Act for the 21st Century (TEA-21) encourage the creation of a stronger
link between land use planning and transportation planning. In many urban areas,
planners from both disciplines are working to achieve this. Planners are able
to develop general goals without too much difficulty. But, they lack a set of
tools to assess the impacts of the alternative land use and transportation scenarios
that are being developed. A "full cost of development" model provides
one approach for comparing the cost of different land use scenarios.
The Federal Highway Administration
has sponsored the development of a prototype model to estimate the full cost of
alternative land use patterns. The EXCEL-based spreadsheet is called the Social
Cost of Alternative Land Development Scenarios (SCALDS) model. The model was developed
under contract with Parsons Brinckerhoff, Quade and Douglas Inc. (PB), building
on three areas of research - least cost planning which has been used by utilities
for a number of years, full cost of travel studies, and cost of service/cost of
sprawl research. The model estimates monetary and non-monetary costs associated
with urban land development at the metropolitan scale. The full cost accounting
framework uses average cost data, derived from a variety of national studies,
as the default values for the calculation of costs.

SCALDS in its present form is a series of interconnected spreadsheets that estimate total costs for three
accounting paths. The first cost estimation path focuses on physical development,
including land consumption, existing and projected housing mix, regional employment,
and local infrastructure capital and operating costs. The second accounting path
estimates the annual peak and non-peak cost of travel on a passenger mile traveled
(PMT) basis. The third path estimates non-dollar denominated costs such as the
air pollution and energy consumption.

The SCALDS model is presently in a prototype form, and is being provided on this web site for downloading and
inspection by public agencies that would like to be considered for beta-testing
of a more refined version which is currently under development. Should an agency
desire to use the prototype version, it is advised to review all the model assumptions
before undertaking applications. It is anticipated that the refined model will
be available for beta-testing by April 1999. A summary paper (30 pages) describing
the model and its operations is also available from this site. In addition, this
site also provides the full report (173 pages) on the research on which the model
is based. If you have comments or questions concerning the model or report please
contact Sam Seskin or Larry Conrad at PB by e-mail at seskin@pbworld.com or conradl@pbworld.com. For more information
on this project contact Patrick DeCorla-Souza at FHWA by e-mail at patrick.decorla-souza@fhwa.dot.gov.

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